You could sell them:
-On Ebay or Craigslist
-To a used camera re-seller if you live in a large city. B&H or Adorama here in NYC, for example.
But the SLRs...
Any college photography program would be very pleased to receive this equipment. Most art schools still teach Photo I (b+w 35mm, wet lab) as a basis for understanding photography... and will do so for quite a while longer.
Speak to the Equipment Room of any local photo program. They can provide you a generous donation receipt and will be happy to take the cameras. Win/win.
If you decide to sell on craigslist or something, try posting right at the beginning of local college semesters. This is when Photo I students begin to search for this equipment. Check out the prices on B&H's used dept., and charge a little less than similar equipment to be fair to the student.